The present invention relates generally to a roller conveyer device and, more specifically, to a roller conveyor device which permits the linear conveyance velocity (i.e., the distance per unit of time at which items are conveyed) to be varied substantially independently of the quantitative conveyance rate (i.e. the number of items conveyed per given unit of time.)
Roller conveyor devices of the type in question generally include a plurality of cylindrical rollers arranged parallel to one another and designed to rotate about their axes. The axes are positioned transverse to the direction of conveyance. The rollers may be designed to spin freely so that, if the roller conveyor device is inclined sufficiently, gravity will effect the necessary movement. Alternatively the rollers may be mechanically driven. By appropriate arrangement of the rollers' axes with respect to one another, for example, by slightly displacing the axes from parallel to one another such that the axes eminate radially from a centerpoint, items may conveyed through a curve.
Although these known techniques of conveyor design are useful in many respects, great difficulty remains in designing a conveyor that operates at a relatively high linear conveyance velocity in one location and a relatively low linear conveyance velocity at a second location, while maintaining a substantially constant and predetermined quantitative conveyance delivery rate throughout the system.
An example of this problem is found in the food product processing industry, specifically in the production of cooked meat pieces such as small steaks or the like. These meat pieces are formed in shaping machines which, for reasons of simplicity, shape only a small number of pieces per operation but have a relatively high operating speed. The pieces are then sent to an oven where the operating speed is considerably lower, because it is desired to avoid a long oven length.
Conventional conveyors impose significant limitations on the extent to which the conveyor's operating speed at the shaping machines can be "geared down" to the conveyor's operating speed at the ovens. With the roller conveyor device based on the present invention, these limitations are substantially avoided with the advantage that more flexible adaptation to the working speed of the oven is attainable and shorter, more efficient ovens can be used in combination with high speed shaping machines.
The invention is, however, not limited to this kind of an application.